The invention relates to a glowswitch starter provided with a discharge vessel which is closed in a gastight manner and which has a wall, with a pair of electrical conductors passed through a portion of the wall of the discharge vessel, and with a bimetal element in the discharge vessel which is conductively connected to one of the electrical conductors, the discharge vessel having an ionizable filling.
Such a glowswitch starter is known from EP 634 884. Such a glowswitch starter may be used, for example, in a device for operating a discharge lamp with preheatable electrodes, in which case the glowswitch starter shunts the discharge lamp and is connected in series with the electrodes. The operation of such a glowswitch starter in such a device is as follows. A glow discharge will be generated between the electrical conductors of the glowswitch starter under the influence of a voltage present across the discharge lamp, after an ignition delay time. This glow discharge heats the bimetal element connected to one of the electrical conductors, which causes said bimetal element to deform such that it makes contact with the other electrical conductor. The creation of this contact extinguishes the glow discharge, and a current will flow through the electrodes of the discharge lamp through the electrical conductors and the bimetal element of the glowswitch starter. This current brings the electrodes of the discharge lamp to a temperature at which an emission of electrons takes place to a degree sufficient for the discharge lamp to ignite. The bimetal element of the glowswitch starter cools down during heating of the electrodes of the discharge lamp and is deformed such that the contact between the two electrical conductors of the glowswitch starter is broken. The interruption of the contact also interrupts the current through the lamp electrodes, and an inductive element connected in series with the lamp generates an ignition voltage pulse. If a discharge between the electrodes of the discharge lamp is initiated by this ignition voltage pulse, the voltage across the discharge lamp, and accordingly the voltage between the electrical conductors of the glowswitch starter, is reduced to the point where no further glow discharge takes place. If no discharge is initiated between the electrodes of the discharge lamp by the ignition voltage pulse, however, the process described above will repeat itself. It is desirable for the ignition delay time which elapses between the moment at which a voltage is offered to the electrical conductors of the glowswitch starter and the moment at which a glow discharge arises to be short, i.e. shorter than 1 s. A hydrogen getter is present for this purpose in the discharge vessel of the known glowswitch starter, which getter comprises an alloy of palladium and zirconium. It is a disadvantage, however, that this requires additional operations for inter alia dosing and applying the getter. Radioactive elements are also used, for example .sup.85 Kr, as an ingredient of the ionizable filling, or Ti.sup.3 H.sub.x on the discharge vessel wall. This measure also involves additional operations, especially because radioactive elements are to be handled with great care for reasons of safety.